This invention relates to medical delivery devices, and in particular, to cannula needle or sheath systems for directed delivery of biomaterials.
Numerous bone conditions or spinal injury can cause painful collapse of vertebral bodies, including osteopenia (osteoporosis), vertebral hemangiomas, multiple myeloma, necorotic lesions (Kummel""s Disease, Avascular Necrosis), metastatic disease and complications from steroid and non-steroidal anti-inflammatory drug (NSAID) use. Osteoporosis is a systemic, progressive and chronic disease that is usually characterized by low bone mineral density, deterioration of bony architecture, and reduced overall bone strength. FIG. 1A depicts the lateral view of typical spinal motion segments 20, with lumbar vertebrae 22, 26, and 28. In contrast, FIG. 1B illustrates a lateral view of a segment of a spinal column that has undergone a vertebral body compression fracture (VCF), as shown by the compressed middle vertebra 26xe2x80x2. VCFs are more common in people who suffer from these medical indications, often resulting in pain, compromises to activities of daily living, and even prolonged disability.
Degenerative and injured spinal disk rehabilitation (pharmacological or gene therapeutic) protocols that delay the progression of intradiscal diseases, or even restore disk health and disk functions, are a part of contemporary research developments and emerging standards of care. The science of spinal intervention has made great strides in recent years. On some occasions, spinal or poly-trauma patients experience VCFs that may be repaired by vertebroplasty and other spinal reconstructive means. Vertebroplasty, which literally means fixing the vertebral body, has been used in the United States since the mid-1990s to treat pain and progressive deterioration associated with VCF. Most often in this vertebroplasty procedure, a bone cement, like opacified polymethylmethacrylate (PMMA), or other suitable biomaterial alternatives or combinations, is injected percutaneously into the bony architecture under radiographic guidance and controls. The hardening (polymerization) of the cement media or the mechanical interlocking of other biomaterials serves to buttress the bony vault of the vertebral body, providing both increased structural integrity and decreased potential for painful micromotion and progressive collapse of the vertebrae and spinal column.
Bone tamps (bone balloons or Kyphoplasty(trademark)), a contemporary balloon-assisted vertebroplasty alternative for treatment of VCF, also involves injection of a bone cement into a mechanically created bone void within vertebral body. In this alternative vertebroplasty procedure, a balloon tamp is first inserted into the structurally compromised vertebral body, often through a cannula. The bone balloon is then inflated under high pressure. It is claimed that the expanding balloon disrupts the cancellous bone architecture and physiological matrix circumferentially and directs the attendant bony debris and physiologic matrix toward the inner cortex of the vertebral body vault. The balloon tamp is then deflated and removed, leaving a bony void or cavity. The remaining void or cavity is repaired by filling it with an appropriate biomaterial media, most often bone cement. In most cases, the treatment goals are to reduce or eliminate pain and the risk of progressive fracture of the vertebral body and its likely resulting morbidity, complications, and disability.
Although most of these interventional procedures are an improvement over previous conservative treatments that consisted of bed rest, pharmaceuticals, and/or cumbersome back braces, these methods still suffer from practical difficulties associated with filling the relevant anatomy with the therapeutic material. The precise direction and placement of the therapeutic media is fundamental to optimal patient outcomes. Iatrogenic injury may be reduced or eliminated by the proper application of a delivery technology. In the case of a damaged vertebral body, it is usually imperative that the injected therapeutic materials, e.g., bone cement, sufficiently fill the distal (anterior) end of the vertebral body since this is where the diseased tissue is normally located. When the delivery device enters the vertebral body from the distal end, the distal opening of the delivery device is often quickly encased and clogged with the therapeutic material. And when the delivery device is positioned proximal of the target site, however, the filling of the cavity is often compromised at the distal end.
Accordingly, it would be desirable to provide treatment systems and methods that allow for improved delivery of therapeutic material in the target treatment site.
The present inventions are directed to a cannula and methods that can be used to deliver therapeutic material to a treatment site in a retrograde manner. Preferably, the inventive cannula is utilized to deliver therapeutic material to bone tissue, such as, e.g., vertebral bodies with compression fractures, but it may also be used at any site in a human or animal that requires the delivery of therapeutic material.
In accordance with a first aspect of the present inventions, the inventive cannula includes a cannula body with a plurality of openings at the distal end that are in fluid communication with a lumen of the cannula body. By way of non-limiting example, the plurality of openings can include a longitudinal opening disposed at the distal tip of the cannula body and one or more transverse openings located proximal to the distal tip. If a plurality of transverse openings are provided, they can be circumferentially offset from each other. The transverse openings can also be arranged into axially spaced groups of transverse openings. The cannula also includes a plunger that is configured to be slidably disposed within a lumen of the cannula body.
Although the present invention should not necessarily be limited by this advantage, the presence of a plurality of openings at the distal end of the cannula body and the plunger provide a means to deliver the therapeutic material to both the proximal and distal ends of the treatment site without having to proximally displace the whole cannula. If there are multiple transverse openings that are circumferentially offset, even perfusion of the therapeutic material is facilitated. In a preferred embodiment, the plunger may include an additional pliable sealable member that provides a tighter seal between the plunger and the inner wall of the cannula body, thereby ensuring or at least minimizing leakage of the therapeutic material between the plunger and the inner wall.
In accordance with a second aspect of the present inventions, a method for delivering implant material into tissue using a cannula is performed. The cannula comprises a cannula body having first and second openings, and a plunger slidably disposed within a lumen of the cannula body. The method comprises inserting the cannula body into a distal section of a tissue, and distally displacing the plunger into a first position distal to the first opening. The implant material is then perfused out of the first opening into the tissue. The plunger is proximally displaced into a second position between the first and second openings, and the implant material is then perfused out of the second opening into the tissue while the plunger is in the second position. By way of non-limiting example, the implant material can be longitudinally perfused out of the first opening, and transversely perfused out of the second opening. This process can be continued if there are any additional openings that are proximal to the second opening. Although the present invention should not necessarily be limited by this advantage, this inventive delivery method provides for a more desirable plume shape of the therapeutic material. Optionally, the distal portion may be separated from the proximal portion of the cannula member, e.g., when the distal tip becomes stuck in the treatment site and it would cause the patient harm if it were to be removed.
In accordance with a third aspect of the invention, the cannula body includes a detachable structure that allows the distal end of the cannula body to be separated from the proximal end. By way of non-limiting example, the detachment structure may include one or more axially spaced notches that allow the cannula body to break into multiple pieces when a shearing force is applied. In a preferred embodiment, the cannula body has a plurality of such notches. Alternatively, the detachment structure may comprise a mechanical junction that would allow the cannula body to separate into multiple pieces when an external force is applied. The mechanical junction may comprise a connective sleeve that detaches into multiple pieces when a shearing or twisting force is applied. In a preferred embodiment, the connective sleeve may contain holes or recessions to aid in the detachment. The mechanical junction may also comprises a threaded junction, wherein the proximal end may be unscrewed from the distal section end. Although the present invention should not necessarily be so limited, the provision of the detachable structure may be desirable when the distal tip becomes stuck in the treatment site and it would cause the patient harm if it were to be removed.
In accordance with a fourth aspect of the invention, a method for delivering implant material into tissue using a cannula is performed. The cannula comprises a cannula body having one or more openings. The method comprises inserting the cannula body into a distal section of a tissue, perfusing the implant material out of the opening into the tissue, and separating the distal end body from the proximal end of the cannula. By way of non-limiting examples, the proximal end is separated from the distal end of the cannula body by detaching the cannula body using a shearing or twisting force or unscrewing the proximal end from the distal end.
Although the present invention should not necessarily be limited by this advantage, this inventive delivery device provides a means for removing the delivery device from the treatment site without further harming the patient if, e.g., the distal tip is intended for implantation or becomes embedded in the treatment site and its removal may pose unnecessary patient risk or threaten patient outcomes if removed.